package editor.cn;

//Given an array of integers nums. 
//
// A pair (i,j) is called good if nums[i] == nums[j] and i < j. 
//
// Return the number of good pairs. 
//
// 
// Example 1: 
//
// 
//Input: nums = [1,2,3,1,1,3]
//Output: 4
//Explanation: There are 4 good pairs (0,3), (0,4), (3,4), (2,5) 0-indexed.
// 
//
// Example 2: 
//
// 
//Input: nums = [1,1,1,1]
//Output: 6
//Explanation: Each pair in the array are good.
// 
//
// Example 3: 
//
// 
//Input: nums = [1,2,3]
//Output: 0
// 
//
// 
// Constraints: 
//
// 
// 1 <= nums.length <= 100 
// 1 <= nums[i] <= 100 
// Related Topics 数组 哈希表 数学 
// 👍 40 👎 0

public class NumberOfGoodPairs{
    public static void main(String[] args) {
        Solution solution = new NumberOfGoodPairs().new Solution();
        System.out.println(solution.numIdenticalPairs(new int[]{1, 2, 3, 1, 1, 3}));
    }

//leetcode submit region begin(Prohibit modification and deletion)
class Solution {
        public int numIdenticalPairs(int[] nums) {
            int count = 0;
        for (int i = 0; i < nums.length; i++) {
            int l = i;
            int r = nums.length - 1;
            while (l < r) {
                if (nums[l] == nums[r]) {
                    count++;
                }
                r--;
            }
        }
            return count;

    }
}
//leetcode submit region end(Prohibit modification and deletion)

}